Java Merge Sort Source Code

I was not able to find a good implementation of merge sort in java as most of the implementations online didn't use comparable and have flags for sorting direction, so I decided to write one of my own.

import java.util.Arrays;

public class MergeSort {

public static void main(String[] args) {

Integer[] a = new Integer[] {3,2,1,4,2,7,1,3,4,5,6,8,9,6,7,8};

sort(a,false);

System.out.println(Arrays.toString(a));

sort(a,true);

System.out.println(Arrays.toString(a));

}

public static void sort(Comparable[] list,boolean asc) {

Comparable[] aux = new Comparable[list.length];

mergeSort(list, aux, 0, list.length-1,asc);

}

private static void mergeSort(Comparable[] list,Comparable[] aux, int start, int end,boolean asc) {

if(end <= start) {

return ;

}

int mid = (start+end)/2;

mergeSort(list,aux,start,mid,asc);

mergeSort(list,aux,mid+1,end,asc);

merge(list,aux,start,mid,end,asc);

}

private static void merge(Comparable[] list, Comparable[] aux, int start, int mid, int end, boolean asc) {

for (int i = start; i <= end; i++) {

aux[i] = list[i];

}

int i = start;

int j = mid + 1;

for (int k = start; k <= end; k++) {

if (i > mid)

list[k] = aux[j++];

else if (j > end)

list[k] = aux[i++];

else if (asc ? aux[j].compareTo(aux[i]) < 0 : aux[j]

.compareTo(aux[i]) > -1)

list[k] = aux[j++];

else

list[k] = aux[i++];

}

}

}